Monte carlo simulation of the coaxial electrons backscattering from thin films

By using the Monte Carlo method, we simulated the trajectories of coaxial backscattering electrons corresponding to a new type of scanning electron microscope. From the calculated results, we obtain a universal expression, which describes with good accuracy the backscattering coefficient versus film thickness under all conditions used. By measuring the coaxial backscattering coefficient and using this universal formula, the thickness of thin films can be determined if the composition is known. Foundation item: Supported by the National Natural Science Foundation of China (No. 993201015) Biography: Hu Da-ping (1957-), male, Ph. D. candidate, research direction: application of computer.     

激光与薄膜靶作用产生X射线阿秒脉冲两种方案的比较

运用一维粒子模拟对经由相对论电子束汤姆逊散射来产生阿秒X射线的两种方案进行了研究。第一种是激光驱动薄膜靶产生相对论电子束以及经过汤姆逊散射产生阿秒X射线,运用倍频探测光的方案可得到更短波长X射线。第二种方案添加了反射厚靶,通过厚靶对驱动激光的反射来减小电子束的横向动量但让其通过,而探测脉冲经过电子束汤姆逊散射后的多普勒频移因子提高,得到的X射线波长也明显减小,光子能量达到1KeV,反射光频谱也明显优与第一种方案．     

The EM scattering from one-dimensionally lossy fractal surfaces

The EM scattering from rough surface has been investigated in the past years. Periodic and random models are often used in modeling the rough surface. Recently, the fractal geometry is rapidly improved. It provides a new way to model the rough surface whose characteristics are long-range order and short-range disorder. In this paper, A fractal function is used to model the rough surface. A scattering coefficient for calculating the angular distribution and the amount of energy in the spectrally scattering field to the fractal characteristics of the surfaces by finding their analytical expressions is derived by using the Kirchhoff solution. In the end, we calculate some scattering patterns. Supported by the National Natural Science Foundation of China Gao Huotao: born in 1964, Graduate student     

A comparison of transition state of phenol in H-atom abstraction by methyl and methylperoxyl radicals

DFT method was employed to locate transition state for H-atom transfer from phenol by methyl radical and methylperoxyl radical. The reaction pathway energy profiles and the structure of transition state show that a common feature is the out-of-plane structure of the transition state: in contrast to the en- ergetic minima of a hydrogen-bonded intermediate, the hydrogen bond in transition structures is con- siderably twisted out of the aromatic ring. From the values of enthalpy (△H) and activation energy (Ea) obtained, it is found that the rate of the reaction of peroxyl radical with phenolic antioxidant is higher than that of alkyl radical with antioxidant. Spin density distributions show that the electron transmis- sion is between methyl (methylperoxyl) radical and phenol.     

Ground observations of post-noon aurora: a case study

The characteristics of the post-noon aurora observed at Antarctic Zhongshan station on June 12, 1999, were discussed and analyzed. In the condition of the magnetic activity is not large (K _p≈1), for post-noon 630.0 nm emissions, the total fluxes of soft precipitating particles were increasing from 10∶50 UT to 13∶35 UT and were decreasing from 13∶35 UT to 18∶00 UT in almost monotonous way. Away from noon, the 557.7 nm emissions increased gradually from 10∶50 UT to 17∶10 UT. The behaviors of the precipitating particles for exciting 630.0 nm aurora and 557.7 nm aurora were quite different. The peak intensity of 630.0 nm and 557.7 nm emissions appeared at about 13∶35 UT and 15∶40 UT respectively, the time difference of two peaks is about 2 h. The energy of precipitating electrons remained fairly steady until 15∶00 UT when it rose dramatically. Foundation item: Support by the National Natural Science Foundation of China (49634160) Biography: Ai Yong (1958-), male, Associate professor, research direction: upper atmosphere physics.     

Real interpolation betweenB-valued martingale Hardy spaces

The interpolation spaces between Banach-space-valued martingale Hardy-spaces, between Hardy and BMO spaces are identified respectively. Some results obtained here are connected closely with the convexity and smoothness of the Banach space which the martingales take values in. Foundation item: Supported by the National Natural Science Foundation of China Biography: YU Lin (1965-), male, Ph. D. Candidate. Current research interests are in geometry of Banach spaces and Banach-spacevalued martingale theory.     

Distributed capacitance of coaxial line with perturbed walls

Perturbation method of boundary geometry (PMOBG) used in Laplacian problems is dealt with and the three-term perturbation expression of, distributed capacitance of a coaxial line with perturbed walls is obtained. As an example, four-order expression of distributed capacitance of a elliptic coaxial line with small eccentricity is given. Foundation item: Supported by the Open Foundation of State Key Laboratory of advanced Technology for Materials Synthersis and Processing Biography: Peng Bao-quan (1943-), male, Associate professor, Research direction electromaganetic field theory and digital signal processing     

第三代场致发光的尝试

为提高发光亮度,本文详细分析了场致发光中的瓶颈过程。发现碰撞激发截面的五个特征:依赖入射电子方向,依赖入射电子能量,依赖发光中心寿命,依赖末态密度,存在不同阈值对不同激发态。并以ZnS:ErF_3的绿、红发光强度比为内标,在有源区外,设置预热层及加速层,选取合适材料,获得及证实了所得过热电子具有较一般结构中更高的平均能量,并对激发截面的某些特征作了实验论证。从实验上直接证明了离化倍增,并计算了它的系数,比文献中报导的都高。它同时显示了采用阴极射线发光材料,以获得彩色发光的可能性。     

Studies of the energy release of mitochondria from sporophyte cytoplasmic male sterile rice by differential scanning calorimetry

The differential scanning calorimetric (DSC) curves of the mitochondria isolated from two varieties of sporophyte cytoplasmic male sterile and their fertile lines of Yie Bai and Ma Xie type rice have been determined. The curves show that the energy is released continuously as temperature rise to 70°C. Some thermodynamic and kinetic parameters of the energy release of the mitochondria have been obtained. The presented results showed that the mitochondria from cytoplasmic male sterile rice released more heat and they had higher energy barrier, less rate, and more complicated mechanism than that of their fertile lines in the energy release process. Foundation item: Supported by the National Natural Science Foundation of China, the China Postdoctoral Science Foundation Biography: Zhou Pei-jiang (1956-), male, PhD, Associate professor. Current resarch interest is in biophysical chemistry and environmental ecological chemistry     

Infrared spectroscopic and theoretical studies on cobalt (II) complex of maleinitriledithiolate and 4, 4′-dimethyl-2, 2′-bipyridine

The complete experimental IR spectra and vibrational analysis of the title complex Co(mnt) (dmbpy) were reported in this paper. The results show that the complex molecule has a planar geometry belonging to point groupC _2v and ground electronic state with spin quartet. A new method for analyzing vibrational spectra of complicated molecule is established. The essential of this method is to point out main fixed points and pivotal vibrational units in assignment for each fundamental band. Two new symbols π (heaving along the specified direction) andM (midpoint of a bond or unit) were defined for describing the vibrational modes accurately. Foundation item: Supported by the National Natural Science Foundation of China (No. 29771025) Biography: Peng Zheng-he(1945-), male, Professor, research direction: functional materials & physical inorganic chemistry.     

The microscopic approach of sdgIBM-1 and its application to nucleus<Superscript>154</Superscript>Gd

Based on the Dyson expansion theory, a microscopic approach of sdgIBM-1 is presented and applied to nucleus¹⁵⁴Gd in this paper. The energy spectra andE2 transition have been calculated. Good agreement is obtained in comparison with experimental results. Foundation item: Supported by the Foundation of Administration of Education of China Biography: Sang Jian ping (1959), male. Ph. D. Professor, research direction: nuclear physics     

碱基与氨基酸二肽间的氢键相互作用

对于碱基-蛋白质之间的相互作用,氢键的形成及断裂起着重要的作用.选取7种氨基酸二肽和3种碱基,以它们之间形成单根氢键的体系为研究对象,在ab initioB3LYP/6-311++G(d,p)水平下进行结构优化,MP2/6-311++G(d,p)水平下进行能量的计算.同时应用ABEEMσπ/MM方法优化结构和计算能量.通过改变氢键相互作用区域的静电相互作用参数kH-bond和形成氢键的氢原子与其受体原子的孤对电子之间距离Rlp,H来拟合函数kH-bond(Rlp,H).用所得函数对选取的复合物进行结合能计算,其结果与ab initio方法所得的结果符合的很好.     

Hausdorff Measure of Linear Cantor Set

We study the Hausdorff measure of linear Cantor set E,on the unit interval,under the strong seperated condition.We give a necessary and sufficient condition for (E) =|E|^α by using the contracting ratio and the first gap.This condition is easy to use.     

炉卷轧机生产X100管线钢的组织特征与强韧性

利用扫描电镜(SEM)、透射电镜(TEM)对炉卷轧机生产X100管线钢的显微组织特点进行了观察与分析,通过背散射电子衍射技术(EBSD)探讨了X100管线钢的有效晶粒尺寸与低温韧性的关系,并利用物理化学相分析的方法对X100管线钢的析出粒子尺寸分布和强化作用进行了定量分析. 结果表明:X100管线钢的显微组织以粒状贝氏体为主,晶粒内部和晶界上弥散分布着大量细小的马氏体/奥氏体(M/A)岛;X100管线钢的有效晶粒尺寸较小,仅为2μm左右,细化有效晶粒尺寸和降低组织方向性有利于提高管线钢的低温韧性;X100管线钢中的析出粒子尺寸较小,平均尺寸为45.4nm,但由于其总体质量分数只有0.062%,经计算,其析出强化作用约为52MPa,析出强化对屈服强度贡献较小.     

Fractal dimension of voice-signal waveforms

The fractal dimension is one important parameter that characterizes waveforms. In this paper, we derive a new method to calculate fractal dimension of digital voice-signal waveforms. We show that fractal dimension is an efficient tool for speaker recognition or speech recognition. It can be used to identify different speakers or distinguish speech. We apply our results to Chinese speaker recognition and numerical experiment shows that fractal dimension is an efficient parameter to characterize individual Chinese speakers. We have developed a semiautomatic voiceprint analysis system based on the theory of this paper and former researches. Foundation item: Supported by the Special Funds for May State Basic Research Projects Biography: Xie Yu-qiong(1964-), female, Ph. D candidate, research direction: fractal geometry.     

Electronic structure of doped trans-polyacetylene

The behavior of electronic structures of doped trans-polyacetylene is revealed by a simple method. (C₂₄H₂₆)⁺ⁿ is used to simulate p-type doped trans-polyacetylene at various doping concentrations. The electronic structure is calculated, by CNDO/2 method. These calculations show that at low doping level, the decrease of electronic energy compensates the increase of elastic energy, thus the bond alternation exists, and the charge carriers are solitons. When doping level is high, the increase of elastic energy is larger than the decrease, of electronic energy, the bond alternation disappears, solitons no longer exist, and polyacetylene is in a metalic state. Foundation item: Supported by the National Natural Science Foundation of China (No. 19834070) Biography: Ren Da-zhi (1948-), male, Associate professor, research direction: solid state physics.     

黄河砂与沙漠砂胶砂强度及微观机理

针对天然砂料日趋枯竭的问题,采用黄河砂和沙漠砂分别全部替代天然砂配置砂浆,通过扫描电镜(scanning electron microscope, SEM)、X-射线能量光谱(energy dispersive spectrometer, EDS)和背散射电子(back scatter electrons, BSE)及元素扫描微观表征手段并联合力学强度试验,从宏微观角度揭示两种砂浆强度发展机理。结果表明：沙漠砂体系中胶砂界面处的钙矾石(AFt)和水化硅酸钙(C-S-H)发育完善,养护前期大量层状Ca(OH)₂紧密堆积,强化了胶砂界面结构;沙漠砂砂浆中的Ca/Si随龄期增加1.64,黄河砂砂浆的钙硅比增加0.52,有效保证其强度稳定性;沙漠砂颗粒黏结性强,充分填充砂浆界面孔隙,优化了砂浆结构的密实性,从而提升了其力学强度。     

Electron acceleration from contracting magnetic islands during reconnection

A long-standing problem in the study of space and astrophysical plasmas is to explain the production of energetic electrons as magnetic fields 'reconnect' and release energy. In the Earth's magnetosphere, electron energies reach hundreds of thousands of electron volts (refs 1-3), whereas the typical electron energies associated with large-scale reconnection-driven flows are just a few electron volts. Recent observations further suggest that these energetic particles are produced in the region where the magnetic field reconnects. In solar flares, upwards of 50 per cent of the energy released can appear as energetic electrons. Here we show that electrons gain kinetic energy by reflecting from the ends of the contracting 'magnetic islands' that form as reconnection proceeds. The mechanism is analogous to the increase of energy of a ball reflecting between two converging walls--the ball gains energy with each bounce. The repetitive interaction of electrons with many islands allows large numbers to be efficiently accelerated to high energy. The back pressure of the energetic electrons throttles reconnection so that the electron energy gain is a large fraction of the released magnetic energy. The resultant energy spectra of electrons take the form of power laws with spectral indices that match the magnetospheric observations.     

铁电材料电畴结构的扫描电镜成象

本文介绍了铁电体电畴结构的扫描电子显微镜成像技术。根据畴反差较弱的特点,着重讨论了样品的处理技术及成像参数的选择技巧。实验结果表明:为了避免畴反差被破坏,必须使用较低的入射电子束能量,较大的入射角和快速帧扫描速度。应用这一技术,成功地在OPTON公司生产的DSM950扫描电镜上观察到了锆钛酸铅二元系压电陶瓷材料90°电畴和180°电畴结构花纹,并且当使用高能电子束轰击未镀导电膜的样品时,能观察到电畴的消失过程。     

Atomic Decompositions of Weak Hardy Spaces of B-Valued Martingales

The atomic decompositions of weak Hardy spaces of Banach-space-valued martingales are given. With the help of the atomic decompositions, some inequalities for B-valued martingales are established in the case 0〈r≤1. Here the results are connected closely with the p-uniform smoothness and q-uniform convexity of Banach spaces which the martingales take values in.